Drilling angled holes on the lathe

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coal miner
Posts: 479
Joined: Tue Mar 18, 2008 6:19 pm
Location: Southern Illinios

Drilling angled holes on the lathe

Post by coal miner » Fri Jul 01, 2011 6:16 pm

Got involved in another project while waiting on some parts for the Farm Boy Engine . This is a sensitive drill press from J . Howells plans that will drill sub # 60 drill holes accurately at up to 7,000 rpm ( if my calculations are right ). Moving along pretty good w/ the parts . He gives some hints and guidance but the tooling and setting up of the operations is left up to the builder . The spindle runs on a 20 tooth gear up and down with a rack cut on the back side of the spindle cartridge. The gear is pinned on the feed rod and had to have a hub w/ 3 1/4"- 20 threaded stainless rods set at 120º spacing on a 16º angle to the feed . I thought about using the rotary table , but the 16º to the shaft axis presented a complex problem to me . I'm sure it would be a piece of cake for someone more learned than me . So sometime time back I had made a drill chuck assem . powered by a cordless drill to fit in a 1" boring block for the Aloris tool post and had used it to drill holes at 90º for set screws for securing hubs to shafts and what not . This would be perfect for this op . The other tool that was used was a degree wheel that had been made to fit in the outboard side of the lathe spindle that had a home made expanding arbor for attaching it .


The hub machined to print and drilling of the holes . Drilling of the holes was easy using the compound . After each hole was drilled , the drill bit was replaced with a 1/4 - 20 tap and the drill switched to the low speed mode and the hole was tapped .

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Even I could figure 0º - 120º - 240º LOL .

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The finished hub mounted on the shaft w/ 2 8 -32 set screws against 90º flats milled on the shaft


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Going to use a variable speed sewing machine motor for power , will have to adjust the mounts to fit .

One of the aspects of this hobby that I really enjoy is figuring how to get the part made and getting the operations in the proper order to get it done . It does strain these old brain cells at times , but I do think it does help my over all mental ability and keeps me from going a little batty . I'll never be an expert at this machining , just as my signature says " the more I learn "
The more I learn , The more I don't know !

Harold_V
Posts: 17793
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Drilling angled holes on the lathe

Post by Harold_V » Fri Jul 01, 2011 11:43 pm

coal miner wrote:I'll never be an expert at this machining
I'm not so sure about that. You display exceptional wisdom and skills.
Very well done!

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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coal miner
Posts: 479
Joined: Tue Mar 18, 2008 6:19 pm
Location: Southern Illinios

Re: Drilling angled holes on the lathe

Post by coal miner » Fri Jul 15, 2011 7:25 pm

Got enough parts made to do a trial assembly of the drill press . No base or parts for for the dial indicator mount , but got to test run and check rpm's , and run-out . The motor is a recyled variable speed Singer sewing machine that the wife had worn the drive parts out . A protective cover still to be made . Initially checking the rpm on it w/the Chinese digital tachometer , came up with 7,000 rpm . An 1/8 " o-ring drive was used . Cut the ends square and after getting to size they were Super Glued together . I made the pulleys about 10% different in diameters w/ the drive pulley being the smaller of the two and read 7800 rpm with the tach . Good enough .
The column lock was made by inserting a piece of brass on the outside circumference of the column shaft bore and after boring to finish size of 1.2495 , it was removed and cut in half providing a machined surface for the lock to mate and tighten with a threaded rod and the handle . The spindle travel limit was an ingenious design that required several small parts made to some very close tolerances , as in tenths , to work right . Several pieces were delegated to the scrap box until they were made proper . LOL A good learning experience .

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The 5/16 " hex spindle shaft is driven by the pulley mounted on a bearing that has a hex brass piece pressed in it that the shaft slides thru for rotation . A broach for this was big $$'s so improvised and made one by cutting steps in a piece of SS hex to push thru after the bulk of the hole was drilled and small holes in the corners inside the inscribed circle were drilled first . This was the first attempt and it had a little play in it , so back to the mill and tightened up the circle to allow for the run-out on the drill bit , and ended up with the one installed .

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The motor mount plates are slotted to allow for alignment of the pulleys and take up for the o-ring drive . The chuck is a Rhome 0 - .250 " keyless w/ a JT1 mount . Making the taper for the JT 1 was another learning experience , but after making the second one and checking it , I thnk it is close enough to swedge on tight w/ some 620 Loctite for insurance .


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Still have quite a bit of blending and smoothing to do , but that is the fun part , working the details .
Mr. Howell shows a cast iron base w/ a magnet made in it , but I think a cross slide table would compliment this drill and give precise set ups . With the dial indicator on the quill feed , very accurate depths can be attained . You can go to Howells website to see the finished machine http://www.model-engine-plans.com/engin ... .htm?21,28

Oh run-out was .0015 , but did not check w/ a bit , the number came straight from the spindle shaft , hopefully with the chuck assembled it will still be good .
The more I learn , The more I don't know !

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coal miner
Posts: 479
Joined: Tue Mar 18, 2008 6:19 pm
Location: Southern Illinios

Re: Drilling angled holes on the lathe

Post by coal miner » Sat Aug 13, 2011 6:26 pm

The plans called for a dial indicator to be incorporated in the spindle to measure drilling depths . Went high tech and adapted a 4" ( smallest I could find ) digital read device to save my eyesight and be easier to read . The quill has 2.150" travel . The Al angle is bolted to the motor block and is slotted to clear the mounting screws on the back of the reader w/ a brass extension over a pin on the spindle slide . The return spring is a little weak but will hold the readout in position . Being able to zero the readout at any position will be handy and this one can be set , once zeroed for reaching a predetermined stopping place , reading down to .000 . That along with the spindle stop on the quill would give one several options on controlling the depth of the hole being drilled . Also purchased a Phase II X-Y table that Enco had on sale . When opened it had a lot of roughness and needed a thorough clean and adjust on the gibs and stoning of the slides . Everything was a lot smoother after that . It is not a top of the line table , but it does have a .001" accuracy in 1.000" cranking the table against a dial indicator . Need to find a piece of plate for the table and the column to mount them on .

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The more I learn , The more I don't know !

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